Method for making oxydiphthalic anhydride

Abstract

Oxydiphthalic anhydride is prepared by effecting contact between a substituted phthalic anhydride such as 4-nitro or 4-fluoro phthalic anhydride and a dialkylaminopyridine in the presence of a refluxing nonpolar organic solvent.

What is claimed and sought to be protected by Letters Patent of the United States is as follows: 
     
       1. A method for making oxydiphthalic anhydride having the formula, ##STR4## which consists of: (1) agitating a mixture comprising a substituted phthalic anhydride of the formula, ##STR5##  a nonpolar organic solvent, and an effective amount of a dialkylaminopyridine having the formula, ##STR6##  at a temperature in the range of from 150° C. to 250° C. to produce a mixture comprising oxydiphthalic anhydride, and (2) recovering the oxydiphthalic anhydride from the mixture of (1), where R and R 1  are members selected from the same or different C.sub.(1-8) alkyl radicals, and X is a member selected from the class consisting of nitro and fluoro.     
     
     
       2. A method in accordance with claim 1, where the dialkylaminopyridine is 4-dimethylaminopyridine. 
     
     
       3. A method in accordance with claim 1, where the nonpolar organic solvent is o-dichlorobenzene. 
     
     
       4. A method in accordance with claim 1, where the oxydiphthalic anhydride is recovered by recrystallization. 
     
     
       5. A method in accordance with claim 1, where the oxydiphthalic anhydride is recovered by sublimitation. 
     
     
       6. A method in accordance with claim 1, where the oxydiphthalic anhydride is recovered by converting the oxydiphthalic anhydride to the tetra acid salt followed by conversion to the tetra acid and dehydration. 
     
     
       7. A method in accordance with claim1, where the substituted phthalic anhydride is 4-nitrophthalic anyhydride. 
     
     
       8. A method in accordance with claim 1, where the substituted phthalic anhydride is 4-fluorophthalic anhydride.